The present invention relates generally to solar arrays used on spacecraft, and more particularly, to improved solar cell circuit layouts and solar cell structures for protecting solar arrays located on spacecraft disposed in geosynchronous earth orbit from electrostatic discharge.
During 1997, the assignee of the present invention launched five high-powered spacecraft which generate over 10 kW of electrical power at the beginning of their life. On two of those spacecraft there has been damage to the solar arrays during the first year of operation. Extensive analysis and ground testing has demonstrated that a damage mechanism exists in which electrostatic discharges occurring between pieces of cover glass and the solar cells on the solar arrays can be sustained by current from the solar array itself. Depending on the physical construction of the array, local heating can cause pyrolization of the insulation which separates the solar cells from the conductive substrate, thus resulting in short circuits of individual strings of solar cells. Susceptibility to this phenomenon is likely to increase throughout the industry as spacecraft power increases lead to larger solar arrays operating at higher voltages. However, analytical modeling and laboratory experimentation have verified the phenomenon and validated the preventative actions undertaken by the assignee of the present invention so that this phenomenon can be controlled on future spacecraft.
It would therefore be desireable to provide for technical approaches that protects solar cells on geosynchronously orbiting spacecraft from damage caused by electrostatic discharge. Accordingly, it is an objective of the present invention to provide for improved solar cell circuit layouts and cell structures for protecting solar arrays located on spacecraft disposed in geosynchronous earth orbit from electrostatic discharge.